The present invention relates to a tachometric device driven by an electric motor.
In more detail, the present invention relates to a tachometric device of the type provided with an electric motor,a shaft of which controls a speed indicator unit by means of a permanent magnet connected to it; this device being likewise provided with a magneto-electric transducer cooperating with the said magnet for the purpose of generating an electric signal usable as negative feedback to control the speed of rotation of the motor shaft.
In known devices of the type specified above the magneto-electric transducer is, in general, constituted by a magnetically actuatable electric switch, a Hall-effect probe, etc. This involves various disadvantages, especially during assembly, during the course of which it is necessary, in particular, correctly to position the transducer with respect to the magnet for the purpose of obtaining, in use, a correct value of the electric feedback signal.